You still haven’t provided any evidence. Your comments in this thread are mostly ideological arguments.
From the article about them directly lobbying against bills on this issue:
==The disclosures show that Intuit as recently as 2011 lobbied on two bills, both of which died, that would have allowed many taxpayers to file pre-filled returns for free. The company also lobbied on bills in 2007 and 2011 that would have barred the Treasury Department, which includes the IRS, from initiating return-free filing.==
There will never be a direct link made because no politician will say, “I am voting against this bill because Intuit took me to a nice dinner and contributed $100k to my re-election campaign.” We do have evidence that constituents want taxes simplified, bills have been presented to fix this problem, companies lobbied against the bills, and the bills died. What’s your theory?
No party has as much direct interest in this issue as tax preparers. That they haven’t been outspent is not itself evidence of anything.
I do agree it is interesting that the GOP campaigned that way, incidentally. Regardless of what degree of support for complicated taxes there may or may not have been, support for simplified taxes in the large, populist wing of the Republican Party plus presumably broad support in the Democratic Party should mean more changes to tax collection soon.
It's not that there can't be such people, it's that there hasn't been any credible evidence provided to prove there actually are such people. That both sides of the political spectrum use the same language is pretty strong evidence that there is broad support ideologically for a simpler tax code.
Bringing up Grover Norquist seems like a red herring, as he is himself a lobbyist. His organization, Americans for Tax Reform, describes itself as a group that "believes in a system in which taxes are simpler, flatter, more visible, and lower than they are today."  Yet, they are used by rayiner as an example of an organization ideologically opposed to simpler taxes and tax filing. If anything, we should be adding ATR's own $5 million of annual spending to the total lobbying dollars being spent against a simpler system.
==should mean more changes to tax collection soon.==
This is the central point. The tax code was just completely overhauled and it included almost zero simplification, even though it's main proponents used that exact messaging in their sales pitch.
The article suggests that the lack of action is, at least in part, because of lobbying. It provides the evidence of lobby spending related to this topic and the ultimate death of those bills. The also have a quote from Former California Republican legislator Tom Campbell, he says he "never saw as clear a case of lobbying power putting private interests first over public benefit."
bribery is the only possible explanation for congress refusing to do what their constituents plainly want.